Permutation defines a protocol for calculating all possible permutations of a given type of data. The protocol may be implemented for any type of custom data which requires the calcuation of permutations (or combintations).

Examples

MapSets are used when members have no inherent order:

iex> mapset = MapSet.new([:paris, :rome, :tokyo, :budapest])
#MapSet<[:budapest, :paris, :rome, :tokyo]>
iex> Permutation.permute(mapset)
{:ok, #MapSet<[#MapSet<[:budapest, :paris, :rome, :tokyo]>]>}

Lists are used when the members ARE ordered:

iex> Permutation.permute([:a, :b, :c])
{:ok,
#MapSet<[
  [:a, :b, :c],
  [:a, :c, :b],
  [:b, :a, :c],
  [:b, :c, :a],
  [:c, :a, :b],
  [:c, :b, :a]
]>}